Not a dumb question at all. Probably the smartest question a prospective scanner buyer can ask.
Without knowing your approximate location, and looking at the system specs, I'll tell you that the SDS series is exactly what you need. It's already a simulcast system, and simulcast systems and sites are only going to increase in the future, so the SDS scanners will do what you want without any concers for the future other than encryption. That depends on what you want to hear, but that system doesn't have nearly as much encryption as some.
I have both the 100 and 200; i criticize them where necessary, and praise them the same. Either of the SDS scanners will give you top-notch results for that system, given average location conditions.